Amending sand with isolite and zeolite under saline conditions: Leachate composition and salt deposition

Understanding the possible influence of inorganic soil amendments on salt l eaching and deposition is helpful in selecting soil amendments when salinit y is a problem. Greenhouse experiments were conducted to: 1) evaluate the e ffects of isolite and zeolite on turf quality of Kentucky bluegrass (Poa pr atensis L.) under three salinity levels; and 2) determine if soil amendment s affected leachate composition, salt deposition, and soil sodium absorptio n ratio (SAR). 'Challenger' Kentucky bluegrass was grown in columns filled with 100% sand, 50 sand : 50 isolite, and 50 sand : 50 zeolite (v/v). Irrig ation waters with three levels of salinity [0.25 (control), 3.5, or 6.5 dS. m(-1)] were applied daily for 3 months in Study I and for 6 months in Study II. Saline water reduced turf quality compared with control. Amendment of sand with isolite increased turf quality only during the third month of tre atment with the most saline water in Study 1. However, zeolite increased tu rf quality during both the second and third months at both salinity levels in both studies. The beneficial effects of zeolite on turf quality diminish ed 5 and 6 months after salinity treatments. Amending sand with zeolite red uced leaching of Na+ and K+, but increased the leaching of Ca2+ and Mg2+. A mending sand with zeolite increased SAR values by 0.9,1.6, and 6.3 units in Study I and 0.9, 3.6, and 10.9 units in Study II, under control, 3.5, and 6.5 dS.m(-1) salinity treatments, respectively. Isolite increased SAR by 1. 1-1.6 units with 3.5 dS.m(-1) and by 2.5-3.5 units with 6.5 dS.m(-1) salini ty treatments. Results indicate that amending with zeolite may buffer soil solution Na+ concentration in the short-term. In the long-term, however, a substantial amount of Na+ may be retained concurrent with Ca2+ and Mg2+ exc hange, thereby increasing sodicity and salinity problems.